The invention relates to a treatment for a web of material or a number of webs of material guided side by side in the nip between treatment rollers, more particularly a web of material impregnated with or containing dye or other finishing agents.
Treatments of this kind are conventional in the finishing of textiles, paper or sheet metal. An example is the so-called foulard process in the dyeing of textiles. A web of textile material is passed through a bath of dye, impregnated with the dye and then treated by pressure in a nip between the treatment rollers of a squeezing press, so that the excess dye is squeezed out of the material and the desired quantity of dye is pressed into the material. This treatment produces a web of material of a uniform shade of colour.
However, there is a need, for example, for webs of textile material having a dye pattern consisting of patches of dye distributed evenly or unevenly over the width and length of the web. These patches of dye differ from one another in the brightness or shade of colour. The intention is that the transitions between the patches should gradually blur, so that the material looks washed out. When a material is treated with glazes, a similar optical effect is desired, to make the material look as though it has worn out. In the past, optical dye and glazing effects of this kind have been produced by hand treating, for example by manually washing the dye out of the material. The dye printing techniques used for obtaining optical effects of this kind would be unjustifiably expensive or simply not possible, in view of the normally considerable width of the webs of material, because of the dimensions of the pattern rollers. For the same reason, changes in design would scarcely be possible.